Color correction during the photographic reproduction of a color image



May 24, 1966 M. A. DE RAMAIX ETAL 3,252,795

COLOR CORRECTION DURING THE PHOTOGRAPH-[C REPRODUCTION OF A COLOR IMAGEFiled NOV. 22, 1965 INVENTOR5 BY mam m, @MA f MQW ATTORNEYS tionresults.

United States Patent O COLUR CORRECTIGN DURING THE PHOTO- GRAPHICREPRODUCTION F A COLR IMAGE Maurice Antoine de Ramaix, Hove-Antwerp, andValre Frans Danckaert, Mortsel-Antwerp, Belgium, assignors to GevaertPhoto-Producten NN., Mortsel-Antwerp, Belgium, a Belgian company FiledNov. 22, 1963, Ser. No. 325,631 Claims priority, application Germany,Dec. 2, 1957, G 23,457, Patent 1,058,839 6 Claims. (Cl. 96-6) Thepresent invention relates to a method of color correction in thereprod-uction of a color image by photographic and/or graphic means andto a photographic element for use therein; this application is .acontinuationin-part of our prior copending application Serial No.777,224, filed December 1, 1958, now abandoned.

It is generally known that on reproducing a colored object in aphotographic way a considerable color devia- In order to reduce thisevil, it is advised to use masks. Besides methods where the two or threemost important masks are obtained separately, which take up much time,it has been proposed to obtain all the necessary masks simultaneously bythe use of a single material. Thus, in `British Patent 562,854, there isproposed a material with two silver halide em-ulsion layers: onesensitive to green and the other sensit-ive to red. The green-sensitiveemulsion could contain either a color coupler for yellow, or for green,or a mixture of a color coupler for yellow and of a color coupler forcyan. It also proposed to add the color couplers for yellow and for cyanto distinct emulsion layers. The red-sensitive emulsion would containeither a color coupler for magenta or for blue, or a mixture of a colorcoupler for magenta and of a color coupler for cyan. It finally proposedto add color couplers for magenta and for cyan, respectively, todistinct layers. The same concept and, in general, the same variationsare described in U.S.P. 2,382,690.

If it is desired to practice the above method where,

the green-sensitive emulsion contains a color coupler for green and thered-sensitive emulsion a color coupler for blue, great difculties arisein finding good color couplers for blue and, above all, for green. Analternative is to use, on the one hand, a mixture of color couplers forcyan and for yellow and, on the other hand, a mixture of color couplersfor cyan and for magenta. But, since it is practically impossible incolor development to have two different color couplers to react in oneand the same emulsion at the same rate, one is thus compelled to make amaterial with four emulsion layers.

It is an object of the present invention to provide a method of colorCorrection during the reproduction of a color image by photographic and/or graphic means wherein the use of a color coupler for blue or green aswell as the use of a mixture of color couplers is avoided without lossof Vthe corresponding advantages.

It is a further object of the present invention to provide aphotographic material which is operative in said method.

Still other objects will appear from the description hereinafter.

These objects are accomplished by the use of a multilayer maskingelement comprising a transparent support carrying thereon a silverhalide emulsion vlayer optically sensitized to both red light and greenlight and containing a color coupler for cyan, a silver halide emulsionlayer optically sensitized to green light and containing a color couplerfor yellow, a blue-sensitive silver halide emulsion layer opticallysensitized to red light and containing a color coupler for magenta anddisposed remote from said support, and a yellow filter layer adjacentsaid ice blue and red-sensitive layer and separating the same from saidtwo other layers.

The present invention thus mainly relates to a process for reproducingcolor images wherein for the photographic reproduction step the colorimage to be reproduced is exposed while in association with a compositemask image containing individual images corresponding, in effect, to thefollowing: a yellow negative of the image to be reproduced obtained bymeans of exposure through a green filter, a magenta negative of thatimage obtained by means of consecutive exposures through a blue and ared filter, and a cyan negative image obtained by consecutive exposuresthrough a green filter and a red filter.

Hereinafter follows in the first example a detailed description of apreferred mode of putting the present invention into practice, without,however, limiting its scope thereto, since numerous variants arepossible, eg. in the sequence of the two layers located between thesupport and the yellow filter layer, in the treatment, etc. The materialof this example is also shown diagrammatically in an accompanyingdrawing to facilitate the understanding thereof.

EXAMPLE l A transparent support having its rear side provided with anantihalation layer is successively coated with the following layers:

(1) An emulsion layer sensitive both to green and to red and containinga color coupler for cyan, such as, for instance,4-sulpho-1-hydroxynaphtho-(2)-octadecylamideg (2) An emulsion layersensitive to green containing a color coupler for yellow, such as, forinstance, m-palmitoylamino-benzoylaceto-3,S-dicarboxyanilide;

(3) A yellow filter layer which contains, for instance, colloidalsilver;

(4) An emulsion layer sensitive both to blue and to red and containing acolor coupler for magenta, such as, for instance,l-p-sulphophenyl-3-octadecyl-pyrazolone-S.

This material is then used in the following Way: the image to bereproduced is printed on it, either by contact or in optical way. Theexposed material is then developed for 5 minutesat 21 C. in a colordeveloper of, for instance, the following composition:

G. N,Ndiethyl-p-phenylenediamine hydrochloride .3 Sodium sulphite(anhydrous) 4 Sodium carbonate (anhydrous) 50 Potassium bromide 1Hydroxylamine hydrochloride l.2

Water to make cm.3.

rinsed for 21/2 minutes in current of water, treated in a bleach-fixingbath which can be composed, for instance of the following composition:

Monosodium ferrie salt of ethylenediamine tetraacetic acid 37.5Trisodium ethylenediarnine tetra-acetate 12.5 Sodium thiosulphate(anhydrous) 100 Sodium sulphite (anhydrous) l() Thiourea 5 Water to make100() cm3.

and finally rinsed for l0 minutes and then dried.

The color-correcting and contrast-reducing mask thus obtained can now beregistered with the color image to be reproduced. The registering of themask and the original can be effected in the usual way, viz the emulsionlayer of the mask is brought into contact either with the rear side orwith the emulsion side of the color dipositive or color negative. lfspecial means for registering the mask are provided it is also possibleto use the masking material according to the invention in an enlarger ora reprocamera for masking purposes in certain circumstances e.g. onmaking separations from a multi-color original in reilex (for instance apainting); afterwards, the mask is put in the optical axis of thecamera. From the combination thus obtained color separations for graphicpurposes or prints upon a three color material (negative or reversaldevelopment) can be made in contact or in optical way.

EXAMPLE 2 In order to demonstrate the functional superiority of thepresent invention over t-he prior art method, a comparison was madebetween a mask element prepared as in Example l above and a mask elementconstructed as in FIG. 4 0f U.S. Patent 2,382,690 and consisting inorder on a support of a red-sensitive emulsion layer containing a cyancoupler, a second red-sensitive emulsion layer containing a magentacoupler, and an exterior green-sensitive layer containing a yellow colorcoupler. The couplers for cyan, magenta, and yellow, respectively, werethe same in both elements and the formulation of the constituents aswell as the processing procedures employed were carried out in as closeto an identical manner as reasonably possible to give a faithfulcomparison Each of the experimental masks so prepared was exposed withwhite light through a glass strip containing three color wedges in thethree complementary colors magenta, cyan and yellow, the dyestuts ofwhich are mixed physically in such a way as to give an absorptioncorresponding to that of the originals from which the separationnegatives are made. After processing, each mask element is registeredwith the glass strip and the registered color wedges are then measuredbehind a blue, green, and a red filter for absolute gamma-values.

For more direct comparison, the absolute gamma-values are adjusted to acommon basis by converting the absolute values for the principalabsorption of each dyestuff, e.g. green light absorption for the magentadyestuf, blue light absorption for the yellow dyestuff, etc. to 100 andmultiplying the absolute gamma-values for the sideabsorptions by thesame conversion factor. The resultant relative gamma-values for the twoexperimental masks, the prior art mask being identified as II and thatof this invention as III, are set forth in the following table togetherwith the corresponding values desired in a theoretically ideal mask,identied as I. A theoretically ideal mask is one giving good colorreproduction, taking into consideration the average side-absorptions ofthe dyestus of the original to be reproduced and the averagesideabsorptions of commercially available printing inks.

Table MASK LAYER RELATIVE GAMMA-VALUES FOR:

Evaluating these results, the following conclusions can be drawn:

(l) As to blue side-absorption by the magenta dyestuff, mask Il iswithin and mask III is just out of the ideal limits;

(2) As to blue side-absorption by the cyan dyestullc,v

mask II shows considerable overcorrection, and mask III is Within theideal limits;

(3) As to green side-absorption by the yellow dyestu?, mask II showssome undercorrection, whereas mask III is within the ideal limits;

(4) As to green side-absorption by the cyan dyestuff, mask II showsconsiderable overcorrection, whereas mask III is within the ideallimits;

(5) As to red side-absorption by the yellow dyestuif, mask II falls justoutside with a slight undercorrection; and mask III falls within theideal limits;

(6) As to the red side-absorption by the magenta dyestuff, mask II showsquite considerable undercorrection and mask III a negligibleundercorrection.

From the above, it will be seen that the two experimental masks givecomparable correction except for blue and green light side-absorptionsby the cyan dyestuff for which mask II provides considerableovercorrection, and for red light side-absorption by the magentadyestuff for which mask II provides considerable undercorrection.

It is clear that due to these considerable correction deviations inthree areas of mask II, mask III exhibits subsantial superiority overmask II.

What we claim is:

1. A multi-layer color photographic masking element for applying colorcorrection during color reproduction comprising a transparent supportcarrying thereon:

(1) a silver halide emulsion layer optically sensitized to both redlight and green light and containing a color coupler for cyan,

(2) a silver halide emulsion layer optically sensitized to green lightand containing a color coupler for yellow,

(3) a blue-sensitive silver halide emulsion layer optically sensitizedto red light and containing a color coupler for magenta and disposedremote from said support, and

(4) a yellow lter layer adjacent said blue-red sensitive layer (3) andseparating the same from said other layers (1) and (2).

2. A color photographic masking element as in claim 1, wherein the colorcoupler for cyan is 4-sulpho-1-hydroxynaphtho-(2)-octadecylamide.

3. A color photographic masking element as in claim 1, wherein the colorcoupler for magenta is l-p-sulphophenyl- 3-octadecyl-pyrazolone-S.

4. A color photographic masking element as in claim 1, wherein the colorcoupler for yellow ism-palmitoylaminobenzoylaceto-3,5-discarboxyanilide.

5. A color photographic masking element comprising on a transparentsupport the following layers in the stated order:

(l) a silver halide emulsion layer optically sensitized to green and tored and containing a coupler for cyan;

(2) a silver halide emulsion layer optically sensitized to green andcontaining a coupler for yellow;

(3) a yellow ilter layer containing colloidal silver; and

(4) a blue-sensitive silver halide emulsion layer optically sensitive tored and containing a color coupler for magenta.

6. In a method of color reproduction of a colored original onlight-sensitive reproduction material, the improvement of etTectingcolor correction in the reproduction coloration by the steps of exposingto said original the masking element of claim 1 and, after colorprocessing of the masking element thus exposed, exposing thelightsensitive reproduction material to said original and the developedmasking element while the latter are in optical registration.

References Cited by the Examiner FOREIGN PATENTS 811,311 4/1959GreatBritain.

NORMAN G. TORCHIN, Primary Examiner.

J. T.,BROWN, Assistant Examiner.

1. A MULTI-LAYER COLOR PHOTOGRAPHIC MASKING ELEMENT FOR APPLYING COLORCORRECTION DURING COLOR REPRODUCTION COMPRISING A TRANSPARENT SUPPORTCARRYING THEREON: (1) A SILVER HALIDE EMULSION LAYER OPTICALLYSENSITIZED TO BOTH RED LIGHT AND GREEN LIGHT AND CONTAINING A COLORCOUPLER FOR CYAN, (2) A SILVER HALIDE EMULSION LAYER OPTICALLYSENSITIZED TO GREEN LIGHT AND CONTAINING A COLOR COUPLER FOR YELLOW, (3)A BLUE-SENSITIVE SILVER HALIDE EMULSION LAYER OPTICALLY SENSITIZED TORED LIGHT AND CONTAINING A COLOR COUPLER FOR MAGENTA AND DISPOSED REMOTEFROM SAID SUPPORT, AND (4) A YELLOW FILTER LAYER ADJACENT SAID BLUE-REDSENSITIVE LAYER (3) AND SEPARATING THE SAME FROM SAID OTHER LAYERS (1)AND (2).
 6. IN A METHOD OF COLOR REPRODUCTION OF A COLORED ORIGINAL ONLIGHT-SENSITIVE REPRODUCTION MATERIAL, THE IMPROVEMENT OF EFFECTINGCOLOR CORRECTION IN THE REPRODUCTION COLORATION BY THE STEPS OF EXPOSINGTO SAID ORIGINAL THE MASKING ELEMENT OF CLAIM 1 AND, AFTER COLORPROCESSING OF THE MASKING ELEMENT THUS EXPOSED, EXPOSING THELIGHTSENSITIVE REPRODUCTION MATERIAL TO SAID ORIGINAL AND THE DEVELOPEDMASKING ELEMENT WHILE THE LATTER ARE IN OPTICAL REGISTRATION.